The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Martin Elsner - One of the best experts on this subject based on the ideXlab platform.
-
compound specific Chlorine Isotope fractionation in biodegradation of atrazine
Environmental Science: Processes & Impacts, 2020Co-Authors: Christina Lihl, Daniel Hunkeler, Benjamin Heckel, Anna Grzybkowska, Agnieszka Dybaladefratyka, Violaine Ponsin, Clara Torrento, Martin ElsnerAbstract:Atrazine is a frequently detected groundwater contaminant. It can be microbially degraded by oxidative dealkylation or by hydrolytic dechlorination. Compound-specific Isotope analysis is a powerful tool to assess its transformation. In previous work, carbon and nitrogen Isotope effects were found to reflect these different transformation pathways. However, Chlorine Isotope fractionation could be a particularly sensitive indicator of natural transformation since Chlorine Isotope effects are fully represented in the molecular average while carbon and nitrogen Isotope effects are diluted by non-reacting atoms. Therefore, this study explored Chlorine Isotope effects during atrazine hydrolysis with Arthrobacter aurescens TC1 and oxidative dealkylation with Rhodococcus sp. NI86/21. Dual element Isotope slopes of Chlorine vs. carbon Isotope fractionation (Λ = 1.7 ± 0.9 vs. Λ = 0.6 ± 0.1) and Chlorine vs. nitrogen Isotope fractionation (Λ = -1.2 ± 0.7 vs. Λ = 0.4 ± 0.2) provided reliable indicators of different pathways. Observed Chlorine Isotope effects in oxidative dealkylation (eCl = -4.3 ± 1.8‰) were surprisingly large, whereas in hydrolysis (eCl = -1.4 ± 0.6‰) they were small, indicating that C-Cl bond cleavage was not the rate-determining step. This demonstrates the importance of constraining expected Isotope effects of new elements before using the approach in the field. Overall, the triple element Isotope information brought forward here enables a more reliable identification of atrazine sources and degradation pathways.
-
compound specific Chlorine Isotope analysis of the herbicides atrazine acetochlor and metolachlor
Analytical Chemistry, 2019Co-Authors: Violaine Ponsin, Christina Lihl, Martin Elsner, Clara Torrento, Daniel HunkelerAbstract:A gas chromatography–single quadrupole mass spectrometry method was developed and validated for compound-specific Chlorine Isotope analysis (Cl-CSIA) of three chlorinated herbicides, atrazine, acet...
-
mechanistic dichotomy in bacterial trichloroethene dechlorination revealed by carbon and Chlorine Isotope effects
Environmental Science & Technology, 2019Co-Authors: Christina Lihl, Martina Daubmeier, Armin H Meyer, Barbara Sherwood Lollar, Lisa M. Douglas, Steffi Franke, Elizabeth A. Edwards, Ivonne Nijenhuis, Alfredo Perezdemora, Martin ElsnerAbstract:Tetrachloroethene (PCE) and trichloroethene (TCE) are significant groundwater contaminants. Microbial reductive dehalogenation at contaminated sites can produce nontoxic ethene but often stops at t...
-
reductive dehalogenation of trichloromethane by two different dehalobacter restrictus strains reveal opposing dual element Isotope effects
Environmental Science & Technology, 2019Co-Authors: Benjamin Heckel, Martin Elsner, Elizabeth J Phillips, Barbara Sherwood Lollar, Elizabeth A. Edwards, Mike Manefield, Matthew K O LeeAbstract:Trichloromethane (TCM) is a frequently detected and persistent groundwater contaminant. Recent studies have reported that two closely related Dehalobacter strains (UNSWDHB and CF) transform TCM to dichloromethane, with inconsistent carbon Isotope effects (e13CUNSWDHB = −4.3 ± 0.45‰; e13CCF = −27.5 ± 0.9‰). This study uses dual element compound specific Isotope analysis (C; Cl) to explore the underlying differences. TCM transformation experiments using strain CF revealed pronounced normal carbon and Chlorine Isotope effects (e13CCF = −27.9 ± 1.7‰; e37ClCF = −4.2 ± 0.2‰). In contrast, small carbon and unprecedented inverse Chlorine Isotope effects were observed for strain UNSWDHB (e13CUNSWDHB = −3.1 ± 0.5‰; e37ClUNSWDHB = 2.5 ± 0.3‰) leading to opposing dual element Isotope slopes (λCF = 6.64 ± 0.14 vs λUNSWDHB = −1.20 ± 0.18). Isotope effects of strain CF were identical to experiments with TCM and Vitamin B12 (e13CVitamin B12 = −26.0 ± 0.9‰, e37ClVitamin B12 = −4.0 ± 0.2‰, λVitamin B12 = 6.46 ± 0.20). Comp...
-
Mechanistic Dichotomy in Bacterial Trichloroethene Dechlorination Revealed by Carbon and Chlorine Isotope Effects
2019Co-Authors: Christina Lihl, Martina Daubmeier, Armin H Meyer, Barbara Sherwood Lollar, Lisa M. Douglas, Steffi Franke, Alfredo Pérez-de-mora, Elizabeth A. Edwards, Ivonne Nijenhuis, Martin ElsnerAbstract:Tetrachloroethene (PCE) and trichloroethene (TCE) are significant groundwater contaminants. Microbial reductive dehalogenation at contaminated sites can produce nontoxic ethene but often stops at toxic cis-1,2-dichloroethene (cis-DCE) or vinyl chloride (VC). The magnitude of carbon relative to Chlorine Isotope effects (as expressed by ΛC/Cl, the slope of δ13C versus δ37Cl regressions) was recently recognized to reveal different reduction mechanisms with vitamin B12 as a model reactant for reductive dehalogenase activity. Large ΛC/Cl values for cis-DCE reflected cob(I)alamin addition followed by protonation, whereas smaller ΛC/Cl values for PCE evidenced cob(I)alamin addition followed by Cl– elimination. This study addressed dehalogenation in actual microorganisms and observed identical large ΛC/Cl values for cis-DCE (ΛC/Cl = 10.0 to 17.8) that contrasted with identical smaller ΛC/Cl for TCE and PCE (ΛC/Cl = 2.3 to 3.8). For TCE, the trend of small ΛC/Cl could even be reversed when mixed cultures were precultivated on VC or DCEs and subsequently confronted with TCE (ΛC/Cl = 9.0 to 18.2). This observation provides explicit evidence that substrate adaptation must have selected for reductive dehalogenases with different mechanistic motifs. The patterns of ΛC/Cl are consistent with practically all studies published to date, while the difference in reaction mechanisms offers a potential answer to the long-standing question of why bioremediation frequently stalls at cis-DCE
Jaime D Barnes - One of the best experts on this subject based on the ideXlab platform.
-
Chlorine Isotope fractionation of the major chloromethane degradation processes in the environment
Environmental Science & Technology, 2020Co-Authors: Frank Keppler, Thierry Nadalig, Markus Greule, Jaime D Barnes, Axel Horst, Enno Bahlmann, Jing Luo, Christoph S Hartmann, Stéphane VuilleumierAbstract:Chloromethane (CH3Cl) is an important source of Chlorine in the stratosphere, but detailed knowledge of the magnitude of its sources and sinks is missing. Here, we measured the stable Chlorine isot...
-
Chlorine Isotope fractionation recorded in atacamite during supergene copper oxidation
Chemical Geology, 2019Co-Authors: Martin Reich, Jaime D Barnes, Daniel O Breecker, Fernando Barra, Catalina Milojevic, Dana L DrewAbstract:Abstract In the Atacama Desert of northern Chile, large amounts of the copper hydroxy-chloride mineral atacamite (Cu2Cl(OH)3) are formed in the supergene oxidation zone of Cu deposits. Since atacamite requires saline water to form and is commonly preserved under hyperarid conditions, it has been proposed as a climate-sensitive mineral marker that can also provide relevant geochemical information regarding halogen (in particular Chlorine) fluid sources during supergene Cu oxidation. However, Chlorine stable Isotope data for atacamite in Cu deposits are scarce and no experimental data for Chlorine Isotope fractionation between atacamite and water are currently available that could provide constraints on the possible mechanisms of fractionation. In this study we report δ37Cl values of atacamite along a thick (~100 m) and well-developed supergene enrichment profile at the Barreal Seco iron oxide-copper-gold (IOCG) deposit in the Atacama Desert. The δ37Cl values of atacamite along this profile range from +2.1‰ to −0.6‰ (mean = +0.4‰ ± 0.7‰; median = +0.3‰), and show a distinct trend with depth, characterized by higher δ37Cl values towards the top of the profile, with lower values at the bottom. In addition, the Chlorine Isotope compositions of experimentally synthetized atacamite crystals and coexisting CuCl2 solutions were determined at room temperature (23 °C). The per mil fractionation factor (Δ37Clatacamite-Cl) was determined at +0.75‰, showing that the heavy Isotope (37Cl) is preferentially incorporated into atacamite. We used numerical models to test two possible scenarios that might explain the observed δ37Cl profile at Barreal Seco. A first scenario involves lowering of the water table with concomitant precipitation of atacamite, which removes Cl from solution following a Rayleigh fractionation process. This model qualitatively fits our observations but does not explain the full magnitude of the observed δ37Cl shift along the supergene profile. In contrast, a model that simulates Cl- diffusion following the upward injection of a deep brine that overlies fresh groundwater reproduces well the observed δ37Cl data, suggesting that seismic pumping of basinal brines, followed by Cl diffusion, is a feasible mechanism to explain the formation of atacamite at Barreal Seco. These data are a first step towards interpreting δ37Cl profiles of atacamite in Cu deposits in the Atacama Desert and exploring the potential use of stable Chlorine Isotopes to monitor Cu weathering and enrichment in supergene environments.
-
sims Chlorine Isotope analyses in melt inclusions from arc settings
Chemical Geology, 2017Co-Authors: Melina Manzini, Jaime D Barnes, Annesophie Bouvier, Magali Bonifacie, Estelle F Rosekoga, Peter Ulmer, Nicole Metrich, Gerard Bardoux, J T Williams, Graham D. LayneAbstract:The relative contribution of volatiles from altered oceanic crust, serpentinized mantle, and subducted sediments on the composition of primary arc magmas is poorly constrained. We measured the Chlorine stable Isotope composition in olivine-hosted melt inclusions in order to provide a first order constraint on the δ37Cl values of primary magmas, since melt inclusions are not or only little affected by near surface processes. Chlorine Isotope analyses were obtained with a CAMECA IMS 1280-HR at the University of Lausanne. A series of six Cl-bearing glass standards with δ37Cl values of − 1.1 to + 1.7‰, SiO2 between 50 and 76 wt% and Cl concentration between 0.15 and 3.25 wt% were used for calibration. We determined that SiO2, Al2O3 and K2O in glasses are primarily responsible for the observed variations in instrumental mass fractionation. We obtained a δ37Cl reproducibility on the standard glasses typically better than 0.3‰ (2SD) and a total uncertainty, corresponding to the propagated error of SIMS and Pyro-IRMS uncertainty, of 0.4‰ (2SD). Melt inclusions from Lesser Antilles, Vanuatu and Aeolian arcs display ranges of δ37Cl values from − 1.9 to + 0.6‰, − 1.7 to + 0.4‰ and − 3.4 to − 1.4‰ respectively. Combined with Cl/K2O ratios, these data suggest that Cl addition mainly originates from serpentinites (lithospheric serpentinites or serpentinized mantle wedge) in the Lesser Antilles and Vanuatu arcs. In contrast, Cl added to the mantle wedge beneath the Aeolian Islands may record a higher proportion of fluids derived from the subducting sediments. The observed differences of δ37Cl values in melt inclusions from the Lesser Antilles and Vanuatu arcs and the Aeolian Islands may directly reflect the different subduction geometries present.
-
Chlorine Isotope geochemistry
Reviews in Mineralogy & Geochemistry, 2017Co-Authors: Jaime D Barnes, Z D SharpAbstract:Chlorine played a prominent role in the discovery of Isotopes. The famous Cavendish Laboratory scientists were fascinated with the atomic mass of Cl. Most elements have a mass that is a close approximation of the multiple of hydrogen (e.g., Aston 1927). By 1920, it was recognized that the atomic weight of Cl was ~35.5, which appeared to violate Francis Aston’s whole number rule. Sir Joseph J. Thomson started the famous “Discussion on Isotopes” (Thomson et al. 1921) with the following: “I will plunge at once into the most dramatic case of the Isotopes—the case of Chlorine”. The discussion that followed between three Nobel Prize winners pitted Thomson against Aston and Frederick Soddy, the latter two in defense of multiple Isotopes of a single element. And so the game began. Aston (1919, 1920) argued that the mass spectra of Cl-bearing compounds (e.g., HCl, COCl) supported the existence of at least two Isotopes of Cl, 35Cl and 37Cl. However, Thomson contended that the spectra may be the result of different compounds of Cl and not necessarily different Isotopes of Cl (Thomson et al. 1921). Ultimately, Aston was proven correct (e.g., Harkins and Hayes 1921; Harkins and Liggett 1923) and is now credited with the discovery of the two stable Isotopes of Cl, which is notable for the unusually large abundance of its “rare” Isotope. The relative abundances of 35Cl and 37Cl are currently accepted to be 75.76% and 24.24%, respectively (Berglund and Wieser 2011). It was not until ~75 years after the discovery of the stable Isotopes of Cl that they become more “routinely” analyzed and the Chlorine Isotope compositions of various Chlorine reservoirs were beginning to be determined. Here we summarize the current state of Chlorine Isotope standards, analytical methods, and fractionation, as well …
-
Chlorine Isotope geochemistry of icelandic thermal fluids implications for geothermal system behavior at divergent plate boundaries
Earth and Planetary Science Letters, 2016Co-Authors: Andri Stefansson, Jaime D BarnesAbstract:Abstract The Chlorine Isotope composition of thermal fluids from Iceland were measured in order to evaluate the source of Chlorine and possible Chlorine Isotope fractionation in geothermal systems at divergent plate boundaries. The geothermal systems studied have a wide range of reservoir temperatures from 40 to 437 °C and in-situ pH of 6.15 to 7.15. Chlorine concentrations range from 5.2 to 171 ppm and δ 37 Cl values are −0.3 to + 2.1 ‰ ( n = 38 ). The δ 37 Cl values of the thermal fluids are interpreted to reflect the source of the Chlorine in the fluids. Geothermal processes such as secondary mineral formation, aqueous and vapor speciation and boiling were found to have minimal effects on the δ 37 Cl values. However, further work is needed on incorporation of Cl into secondary minerals and its effect on Cl Isotope fractionation. Results of Isotope geochemical modeling demonstrate that the range of δ 37 Cl values documented in the natural thermal fluids can be explained by leaching of the basaltic rocks by meteoric source water under geothermal conditions. Magmatic gas partitioning may also contribute to the source of Cl in some cases. The range of δ 37 Cl values of the fluids result mainly from the large range of δ 37 Cl values observed for Icelandic basalts, which range from −0.6 to + 1.2 ‰ .
Daniel Hunkeler - One of the best experts on this subject based on the ideXlab platform.
-
tracking chlorinated contaminants in the subsurface using compound specific Chlorine Isotope analysis a review of principles current challenges and applications
Chemosphere, 2020Co-Authors: Jeremy Zimmermann, Landon J S Halloran, Daniel HunkelerAbstract:Many chlorinated hydrocarbons have gained notoriety as persistent organic pollutants in the environment. Engineered and natural remediation efforts require a monitoring tool to track the progress of degradation processes. Compound-specific Isotope analysis (CSIA) is a robust method to evaluate the origin and fate of contaminants in the environment and does not rely on concentration measurements. While carbon CSIA has established itself in the routine assessment of contaminated sites, studies incorporating Chlorine Isotopes have only recently become more common. Although some aspects of Chlorine Isotope analysis are more challenging than carbon Isotope analysis, having additional isotopic data yields valuable information for contaminated site management. This review provides an overview of Chlorine Isotope fractionation of chlorinated contaminants in the subsurface by different processes and presents analytical techniques and unresolved challenges in Chlorine Isotope analysis. A summary of successful field applications illustrates the potential of using Chlorine Isotope data. Finally, approaches in modelling Chlorine Isotope fractionation due to degradation, diffusion, and sorption processes are discussed.
-
compound specific Chlorine Isotope fractionation in biodegradation of atrazine
Environmental Science: Processes & Impacts, 2020Co-Authors: Christina Lihl, Daniel Hunkeler, Benjamin Heckel, Anna Grzybkowska, Agnieszka Dybaladefratyka, Violaine Ponsin, Clara Torrento, Martin ElsnerAbstract:Atrazine is a frequently detected groundwater contaminant. It can be microbially degraded by oxidative dealkylation or by hydrolytic dechlorination. Compound-specific Isotope analysis is a powerful tool to assess its transformation. In previous work, carbon and nitrogen Isotope effects were found to reflect these different transformation pathways. However, Chlorine Isotope fractionation could be a particularly sensitive indicator of natural transformation since Chlorine Isotope effects are fully represented in the molecular average while carbon and nitrogen Isotope effects are diluted by non-reacting atoms. Therefore, this study explored Chlorine Isotope effects during atrazine hydrolysis with Arthrobacter aurescens TC1 and oxidative dealkylation with Rhodococcus sp. NI86/21. Dual element Isotope slopes of Chlorine vs. carbon Isotope fractionation (Λ = 1.7 ± 0.9 vs. Λ = 0.6 ± 0.1) and Chlorine vs. nitrogen Isotope fractionation (Λ = -1.2 ± 0.7 vs. Λ = 0.4 ± 0.2) provided reliable indicators of different pathways. Observed Chlorine Isotope effects in oxidative dealkylation (eCl = -4.3 ± 1.8‰) were surprisingly large, whereas in hydrolysis (eCl = -1.4 ± 0.6‰) they were small, indicating that C-Cl bond cleavage was not the rate-determining step. This demonstrates the importance of constraining expected Isotope effects of new elements before using the approach in the field. Overall, the triple element Isotope information brought forward here enables a more reliable identification of atrazine sources and degradation pathways.
-
compound specific Chlorine Isotope analysis of the herbicides atrazine acetochlor and metolachlor
Analytical Chemistry, 2019Co-Authors: Violaine Ponsin, Christina Lihl, Martin Elsner, Clara Torrento, Daniel HunkelerAbstract:A gas chromatography–single quadrupole mass spectrometry method was developed and validated for compound-specific Chlorine Isotope analysis (Cl-CSIA) of three chlorinated herbicides, atrazine, acet...
-
carbon and Chlorine Isotope fractionation patterns associated with different engineered chloroform transformation reactions
Environmental Science & Technology, 2017Co-Authors: Clara Torrento, Martin Elsner, Benjamin Heckel, Jordi Palau, Diana Rodriguezfernandez, Armin H Meyer, Cristina Domenech, Monica Rosell, Albert Soler, Daniel HunkelerAbstract:To use compound-specific Isotope analysis for confidently assessing organic contaminant attenuation in the environment, Isotope fractionation patterns associated with different transformation mechanisms must first be explored in laboratory experiments. To deliver this information for the common groundwater contaminant chloroform (CF), this study investigated for the first time both carbon and Chlorine Isotope fractionation for three different engineered reactions: oxidative C–H bond cleavage using heat-activated persulfate, transformation under alkaline conditions (pH ∼ 12) and reductive C–Cl bond cleavage by cast zerovalent iron, Fe(0). Carbon and Chlorine Isotope fractionation values were −8 ± 1‰ and −0.44 ± 0.06‰ for oxidation, −57 ± 5‰ and −4.4 ± 0.4‰ for alkaline hydrolysis (pH 11.84 ± 0.03), and −33 ± 11‰ and −3 ± 1‰ for dechlorination, respectively. Carbon and Chlorine apparent kinetic Isotope effects (AKIEs) were in general agreement with expected mechanisms (C–H bond cleavage in oxidation by pers...
-
compound specific Chlorine Isotope analysis of tetrachloromethane and trichloromethane by gas chromatography Isotope ratio mass spectrometry vs gas chromatography quadrupole mass spectrometry method development and evaluation of precision and truenes
Analytical Chemistry, 2017Co-Authors: Benjamin Heckel, Daniel Hunkeler, Clara Torrento, Jordi Palau, Diana Rodriguezfernandez, Armin H Meyer, Cristina Domenech, Monica Rosell, Albert Soler, Martin ElsnerAbstract:Compound-specific Chlorine Isotope analysis of tetrachloromethane (CCl4) and trichloromethane (CHCl3) was explored by both, gas chromatography-Isotope ratio mass spectrometry (GC-IRMS) and GC-quadrupole MS (GC-qMS), where GC-qMS was validated in an interlaboratory comparison between Munich and Neuchâtel with the same type of commercial GC-qMS instrument. GC-IRMS measurements analyzed CCl isotopologue ions, whereas GC-qMS analyzed the isotopologue ions CCl3, CCl2, CCl (of CCl4) and CHCl3, CHCl2, CHCl (of CHCl3), respectively. Lowest amount dependence (good linearity) was obtained (i) in H-containing fragment ions where interference of 35Cl- to 37Cl-containing ions was avoided; (ii) with tuning parameters favoring one predominant rather than multiple fragment ions in the mass spectra. Optimized GC-qMS parameters (dwell time 70 ms, 2 most abundant ions) resulted in standard deviations of 0.2‰ (CHCl3) and 0.4‰ (CCl4), which are only about twice as large as 0.1‰ and 0.2‰ for GC-IRMS. To compare also the truene...
Orjan Gustafsson - One of the best experts on this subject based on the ideXlab platform.
-
carbon and Chlorine Isotope fractionation during microbial degradation of tetra and trichloroethene
Environmental Science & Technology, 2013Co-Authors: Charline Wiegert, Henry Holmstrand, Manolis Mandalakis, Christoph Aeppli, Timothy D J Knowles, Paraskevi N Polymenakou, Jiřina Machackova, Richard P Evershed, R D Pancost, Orjan GustafssonAbstract:Two-dimensional compound-specific Isotope analysis (2D-CSIA), combining stable carbon and Chlorine Isotopes, holds potential for monitoring of natural attenuation of chlorinated ethenes (CEs), in c ...
-
Chlorine Isotope effects and composition of naturally produced organoChlorines from chloroperoxidases flavin dependent halogenases and in forest soil
Environmental Science & Technology, 2013Co-Authors: Christoph Aeppli, Per Andersson, David Bastviken, Orjan GustafssonAbstract:The use of stable Chlorine isotopic signatures (delta Cl-37) of organoChlorine compounds has been suggested as a tool to determine both their origins and transformations in the environment. Here we ...
-
Chlorine Isotope evidence for the anthropogenic origin of tris 4 chlorophenyl methane
Applied Geochemistry, 2010Co-Authors: Henry Holmstrand, Manolis Mandalakis, Zdenek Zencak, Per Andersson, Orjan GustafssonAbstract:Abstract Compound-specific Cl-Isotope analysis was performed on the persistent and bioaccumulating compound tris-(4-chlorophenyl)methane (4,4′,4″-TCPMe, referred to as TCPMe in this study) to elucidate whether its main source is natural or anthropogenic. Blubber from the Baltic grey seal (Halichoerus grypus) was extracted by continuous acetonitrile partitioning, and the TCPMe was isolated from the extract by preparative-capillary gas chromatography. Chlorine Isotope analysis was subsequently performed by sealed-tube combustion in conjunction with thermal-ionization mass spectrometry (TIMS). The δ37Cl of TCPMe was −3.5 ± 0.5‰, similar to the previously reported δ37Cl of technical grade p,p′-DDT (referred to as DDT in this study). The data is not consistent with a putative marine natural source of TCPMe, as enzymatic (biotic) production is reported to give values of δ37Cl
-
direct compound specific stable Chlorine Isotope analysis of organic compounds with quadrupole gc ms using standard Isotope bracketing
Analytical Chemistry, 2010Co-Authors: Christoph Aeppli, Henry Holmstrand, Per Andersson, Orjan GustafssonAbstract:A method has been developed for the direct determination of the stable Chlorine Isotope composition (delta(37)Cl) of organoChlorines that eliminates sample preparation, achieves precision comparable to earlier techniques while improving the sensitivity, and makes use of benchtop gas chromatography-quadrupole mass spectrometry instruments (GCqMS). The method is based on the use of multiple injections (n = 8-10) of the sample, bracketed by a molecularly identical isotopic standard with known delta(37)Cl, determined using off-line thermal ionization mass spectrometry (TIMS). Mass traces of two isotopologues differing by one Chlorine Isotope were used to calculate delta(37)Cl values. Optimization of mass spectrometry and peak integration parameters as well as method validation was achieved using tetrachloroethene (PCE), p,p'-dichlorodiphenyltrichloroethane (DDT), and pentachlorophenol (PCP), spanning a delta(37)Cl range of -5.5 to +3.2 per thousand vs SMOC. Injecting 1.6-1100 pmol resulted in standard deviations (1sigma) of 0.6-1.3 per thousand, and the delta(37)Cl results agreed with values independently measured with TIMS. The method was tested by determining the Rayleigh fractionation during evaporation of pure liquid PCE, resulting in a Chlorine isotopic enrichment factor of epsilon(Cl) = -1.1 +/- 0.4 per thousand. Furthermore, position-specific delta(37)Cl analysis based on analysis of DDT mass fragments was evaluated. The GCqMS-delta(37)Cl method offers a simplified yet sensitive approach for compound-specific Chlorine Isotope analysis.
-
compound specific Chlorine Isotope analysis of polychlorinated biphenyls isolated from aroclor and clophen technical mixtures
Chemosphere, 2008Co-Authors: Manolis Mandalakis, Henry Holmstrand, Per Andersson, Orjan GustafssonAbstract:Compound-specific Chlorine Isotope analysis (CSIA–Cl) is promising as a novel and powerful method for monitoring in situ degradation of organoChlorines in the environment and for source fingerprinting purposes. In order to apply CSIA–Cl in field studies of polychlorinated biphenyls (PCBs), the Chlorine isotopic composition (δ37Cl) of individual PCB congeners in source materials must be known. In the present study, we determined δ37Cl of 18 congeners isolated from three widely produced technical mixtures. All congeners provided δ37Cl ranging between −1.9‰ and −3.5‰. Although the comparable products Aroclor 1242 (−2.0‰ to −2.5‰) and Clophen A30 (−1.9‰ to −3.0‰) were synthesized by different industries, they provided similar δ37Cl for the same type of congeners. On the contrary, the more chlorinated congeners present in Aroclor 1254 (−2.1 to −3.5‰) were more 37Cl depleted compared to Aroclor 1242 manufactured by the same company. Overall, δ37Cl of PCB congeners decreased by −0.26 ‰ for each additional Chlorine atom.
Henry Holmstrand - One of the best experts on this subject based on the ideXlab platform.
-
stable Chlorine Isotope analysis of chlorinated acetic acids using gas chromatography quadrupole mass spectrometry
Rapid Communications in Mass Spectrometry, 2015Co-Authors: Milena E Miska, Orfan Shouakarstash, Henry HolmstrandAbstract:Rationale The environmental occurrence of chlorinated acetic acids (CAAs) has been extensively studied, but the sources and transport are still not yet fully understood. A promising approach for source apportionment and process studies is the isotopic characterization of target compounds. We present the first on-line stable Chlorine Isotope analysis of CAAs by use of gas chromatography/quadrupole mass spectrometry (GC/qMS). Methods Following approved procedures for concentration analysis, CAAs extracted into MTBE were methylated to GC-amenable methyl esters (mCAAs). These mCAAs were then analyzed by GC/qMS for their stable Chlorine Isotope composition using a sample/standard-bracketing approach (CAA standards in the range δ37Cl −6.3 to −0.2 ‰, Standard Mean Ocean Chloride). Results Cross-calibration of the herein presented method with off-line reference methods (thermal ionization and continuous-flow GC Isotope ratio mass spectrometry; TI-MS and CF-GC/IRMS, respectively) shows good agreement between the methods (regression slope for GC/qMS vs reference method data sets: 0.92 ± 0.29). Sample amounts as small as 10 pmol Cl can herewith be analyzed with a precision of 0.1 to 0.4 ‰. Conclusions This method should be useful for environmental studies of CAAs at ambient concentrations in precipitations (<0.06 to 100 nmol L–1), surface waters (<0.2 to 5 nmol L–1) and soil (<0.6 to 2000 nmol kg–1 dry soil) where conventional off-line methods cannot be applied. Copyright © 2015 John Wiley & Sons, Ltd.
-
carbon and Chlorine Isotope fractionation during microbial degradation of tetra and trichloroethene
Environmental Science & Technology, 2013Co-Authors: Charline Wiegert, Henry Holmstrand, Manolis Mandalakis, Christoph Aeppli, Timothy D J Knowles, Paraskevi N Polymenakou, Jiřina Machackova, Richard P Evershed, R D Pancost, Orjan GustafssonAbstract:Two-dimensional compound-specific Isotope analysis (2D-CSIA), combining stable carbon and Chlorine Isotopes, holds potential for monitoring of natural attenuation of chlorinated ethenes (CEs), in c ...
-
Chlorine Isotope evidence for the anthropogenic origin of tris 4 chlorophenyl methane
Applied Geochemistry, 2010Co-Authors: Henry Holmstrand, Manolis Mandalakis, Zdenek Zencak, Per Andersson, Orjan GustafssonAbstract:Abstract Compound-specific Cl-Isotope analysis was performed on the persistent and bioaccumulating compound tris-(4-chlorophenyl)methane (4,4′,4″-TCPMe, referred to as TCPMe in this study) to elucidate whether its main source is natural or anthropogenic. Blubber from the Baltic grey seal (Halichoerus grypus) was extracted by continuous acetonitrile partitioning, and the TCPMe was isolated from the extract by preparative-capillary gas chromatography. Chlorine Isotope analysis was subsequently performed by sealed-tube combustion in conjunction with thermal-ionization mass spectrometry (TIMS). The δ37Cl of TCPMe was −3.5 ± 0.5‰, similar to the previously reported δ37Cl of technical grade p,p′-DDT (referred to as DDT in this study). The data is not consistent with a putative marine natural source of TCPMe, as enzymatic (biotic) production is reported to give values of δ37Cl
-
direct compound specific stable Chlorine Isotope analysis of organic compounds with quadrupole gc ms using standard Isotope bracketing
Analytical Chemistry, 2010Co-Authors: Christoph Aeppli, Henry Holmstrand, Per Andersson, Orjan GustafssonAbstract:A method has been developed for the direct determination of the stable Chlorine Isotope composition (delta(37)Cl) of organoChlorines that eliminates sample preparation, achieves precision comparable to earlier techniques while improving the sensitivity, and makes use of benchtop gas chromatography-quadrupole mass spectrometry instruments (GCqMS). The method is based on the use of multiple injections (n = 8-10) of the sample, bracketed by a molecularly identical isotopic standard with known delta(37)Cl, determined using off-line thermal ionization mass spectrometry (TIMS). Mass traces of two isotopologues differing by one Chlorine Isotope were used to calculate delta(37)Cl values. Optimization of mass spectrometry and peak integration parameters as well as method validation was achieved using tetrachloroethene (PCE), p,p'-dichlorodiphenyltrichloroethane (DDT), and pentachlorophenol (PCP), spanning a delta(37)Cl range of -5.5 to +3.2 per thousand vs SMOC. Injecting 1.6-1100 pmol resulted in standard deviations (1sigma) of 0.6-1.3 per thousand, and the delta(37)Cl results agreed with values independently measured with TIMS. The method was tested by determining the Rayleigh fractionation during evaporation of pure liquid PCE, resulting in a Chlorine isotopic enrichment factor of epsilon(Cl) = -1.1 +/- 0.4 per thousand. Furthermore, position-specific delta(37)Cl analysis based on analysis of DDT mass fragments was evaluated. The GCqMS-delta(37)Cl method offers a simplified yet sensitive approach for compound-specific Chlorine Isotope analysis.
-
compound specific Chlorine Isotope analysis of polychlorinated biphenyls isolated from aroclor and clophen technical mixtures
Chemosphere, 2008Co-Authors: Manolis Mandalakis, Henry Holmstrand, Per Andersson, Orjan GustafssonAbstract:Compound-specific Chlorine Isotope analysis (CSIA–Cl) is promising as a novel and powerful method for monitoring in situ degradation of organoChlorines in the environment and for source fingerprinting purposes. In order to apply CSIA–Cl in field studies of polychlorinated biphenyls (PCBs), the Chlorine isotopic composition (δ37Cl) of individual PCB congeners in source materials must be known. In the present study, we determined δ37Cl of 18 congeners isolated from three widely produced technical mixtures. All congeners provided δ37Cl ranging between −1.9‰ and −3.5‰. Although the comparable products Aroclor 1242 (−2.0‰ to −2.5‰) and Clophen A30 (−1.9‰ to −3.0‰) were synthesized by different industries, they provided similar δ37Cl for the same type of congeners. On the contrary, the more chlorinated congeners present in Aroclor 1254 (−2.1 to −3.5‰) were more 37Cl depleted compared to Aroclor 1242 manufactured by the same company. Overall, δ37Cl of PCB congeners decreased by −0.26 ‰ for each additional Chlorine atom.